Bell's Palsy (originally described by Charles Bell, 1812) is recognized as a palsy of the facial nerve, generally the seventh cranial nerve. It most commonly affects one side of the face, may be partial or total, and has a progression time of 7 to 10 days. Regarded in the past as idiopathic, there has recently been convincing evidence that it has its cause in the herpes type virus of the simplex type. Some physicians reassure patients that the disease will most likely remit in a period lasting from 3 weeks up to 6 months, (leading some physicians to advocate a no action policy other than facial management, sometimes referred to as "therapeutic nihilism") but the fact remains that about 24% of the victims with current popular therapies are left with some residual paralysis or other aftereffects such as hemi-facial spasm, synkinesis, or loss of tearing or blinking capacity.
An understanding as to the likely physiological events (without an identification of their cause) was comprehensively put forward by Hilger (Hilger J, The Nature of Bell's Palsy. Laryngoscope, 54:228-235, 1949) and Blunt (Blunt M, Possible Role of Vascular Changes in the Etiology of Bell's Palsy, J. Laryngol Otol, 70:701-713, 1956)) where they maintained that vasoconstriction of the arterioles within the fallopian aqueduct of the temporal bone was responsible for the facial palsy. This vasoconstriction was believed to lead to primary ischemia (tissue anemia) entailing edema of the nerve sheath and a secondary ischemia due to nerve compression. K. Adour opposed this account and instead put forward a viral theory (Adour K K, Cranial Polyneuritus and Bell's Palsy, Arch Otolarygol, 102:262-4, 1976) based on herpes simplex reactivation and maintained that Bell's Palsy was polycranial which was believed to be inconsistent with an ischemia scenario. However, support of the former ischemia outlook was provided through anatomical electromyographical and histopathological studies summarized by U. Fisch (Fisch U. and Felix, H, On the Parthenogenesis of Bell's Palsy. Acta Otolaryngol, 95:532-538, 1983)). Further the ischemia description of events fits well with later causal analysis by M. Ikeda (Ikeda M et al, Plasma Endothelin Level in the Acute Stage of Bell Palsy, Arch Otolyaryngol Head Neck Surg, 122:849-852, August 1996) involving endothelin findings; and work on the immunological role of endothelin has been inferentially linked by the inventor to an ischemia scenario (which requires--a herpes viral role) as will be later explained.
Current therapy mainly involves the administration of steroids, particularly prednisone (see U.S. Pat. No. 2,897,216) within the first 3 days of onset, where the standard initial prednisone dosage is about 30 mg. and is tapered off over a 5 day period to a 10 mg. level. In parts of Japan and Europe the steroid treatment has taken the form of heavier steroid dosages, mainly cortisone, incorporated within an IV infusion of low molecular dextran (Kinishi M et al., Conservative Treatment of Hunt Syndrome, Nippon Jibinkoka Gakkai Kaiho, 95:1, 65-70, 1992) (See U.S. Pat. No. 2,841,578). The theory underlying steroid treatment, either by prednisone or the higher dosage method, is to improve microcirculation, which has been impaired due to inflammation affecting the seventh cranial nerve. It may be noted that steroid treatment of the high dosage type has its share of hazards that leave many physicians uncomfortable, and which includes serious hepatic and renal disorders.
Recently a new element of approach that is coupled with steroid therapy has emerged from the work of Dr. Kedar Adour, who for many years had maintained that the herpes simplex virus is the original causal agent in Bell's Palsy. Based on this belief, Adour has advocated the use of acyclovir (See U.S. Pat. No. 2,539,963) (commonly used for treating herpes viral infections) for treating Bell's Palsy. He has in this effort conducted a double blind study (Adour K K et al., Bell's Palsy Treatment With Acyclovir And Prednisone Compared With Prednisone Alone: A Double-Blind, Randomized Controlled Trial. Otol Rhinol. Larygnol 1996;105:371-378.) (Kaiser Permanente Medical Center), which provides viable support for the use of acyclovir, an established herpes virus inhibitor. The study compared an acyclovir-prednisone group of subjects with a prednisone-placebo group and the following results were obtained: a 92% volitional motion recovery rate for the acyclovir group versus 76% for the prednisone-placebo group, and an 87% prevention rate of nerve degeneration for acyclovir-prednisone versus 70% for prednisone-placebo. Although the number of subjects was one hundred, about equally split in the 2 groups, results are both statistically significant and in agreement with other studies supporting a herpes simplex or herpes family origins of Bell's Palsy. These studies include the work of Sugita (Sugita T et al, Facial Nerve Paralysis Induced by Herpes Simplex Virus in Mice: An Animal Model of Acute Transient Facial Paralysis, Ann Otol Rhinol Laryngol 104(7):574-581, July 1995) inducing apparent Bell's Palsy in mice with herpes simplex and the work of Murakami, pointing chiefly to herpes simplex but sometimes invoking other herpes viruses.
Further, recently there has been a significant study by M. Ikeda (Nihon University School of Medicine, Tokyo Japan) linking endothelin, a peptide of 21 amino acids with Bell's Palsy. This study is yet to receive sufficient attention, however it sheds important light on some of the immediate causal events underlying Bell's Palsy. Endothelin is an extremely potent constrictor of blood vessels, particularly smaller ones, and Ikeda maintains that impairment of microcirculation through primary and secondary ischemia in the fallopian aqueduct (and thereby drawing on the earlier work of Hilger and Blunt) is responsible, but what is new here is the role of endothelin in bringing this about. Ikeda, however, regards the etiology of Bell's Palsy as unknown or idiopathic, and does not offer any causal hypotheses for the high endothelin levels.
There are some other current therapies in addition to steroids, but they do not enjoy a similar popularity, although they are occasionally used in conjunction with it. This includes surgical decompression, more prevalent in previous decades, beginning in the thirties, although sometimes still employed (Jabor M A, Management of Bell's Palsy, J LA State Medical Soc, 146(7): 279-283, 1996) where damage is assessed as extensive. Additionally included is electrical stimulation (also used in previous decades (Devrese P P et al., Electrotherapy in Facial Paralysis, ORL Otorhinolarygol Relat Spec, 1974; 36(2): 94-99) acupuncture and biofeedback (May M, et al, Bell's Palsy: Management of Sequelae Using EMG. Rehabilitation, Bottulinum and Surgery , Am J Otol, 10(3):220-229, May 1989)). There appears to be no conclusive studies on these techniques and anecdotal evidence is at best mixed. As for surgery, it has its special hazards, while being based upon the ischemia hypothesis.
In addition to the discussed therapies designed to alleviate or minimize damage, management approaches including eye patches and artificial tears are almost invariably offered to avoid permanent eye damage. Electrical conductivity tests are also used and are of significant value in assessing permanent nerve damage of degeneration. Facial massage is sometimes also recommended to aid in circulation and avoid atrophy once muscle movement returns.
There have been 4 patents (U.S. Pat. Nos. 5,589,183, 5,542,437, 5,148,477, 4,817,628) since 1971 that deal with Bell's Palsy. Of the four, two deal with facial management by mechanical devices, and two are electrically diagnostic for assessment purposes.
Ramsay Hunt syndrome (also known as "herpes zoster oticus") is also caused by a herpes virus, but in this case the herpes zoster virus, as was maintained (the condition) by J. Ramsay Hunt in 1907. Ramsay Hunt syndrome frequently results in facial paralysis involving the seventh cranial nerve (as with Bell's Palsy) but also commonly affects other cranial nerves including the 5th 9th and 10th and 11th). (Further, it should be noted that Ramsay Hunt syndrome as referred to in this invention is Ramsay Hunt Type I, not to be confused with Ramsay Hunt Type II, an entirely different condition which is a rare degenerative neurological disorder characterized by epileptic type fits and myoclonus.) Ramsay Hunt is often accompanied at onset by auricular vesicles, sometimes also found on face, neck or scalp and frequently results in hearing loss (48.2% according to S. Murakami). (Murakami S. et al., Clinical features and Prognosis of Facial Palsy and Hearing Loss in Patients With Ramsay Hunt, Nippon Jibiinkoka Gakkao, 99:12, 1772-1779, December 1996) Intense ear pain and vertigo and tinnitus are also common manifestations. Ramsay Hunt in relation to facial paralysis of the seventh cranial nerve (as with Bell's palsy) is found to have a less favorable recovery profile than the latter (Robillard R B et al., Ramsay Hunt Facial Paralysis: "Clinical Analysis of 185 Patients, Otolaryngol Head Neck Surg, 95 (3pt1):292-297, October 1986) Complete recovery rates are estimated at about 52% (Murakami S. Nippon Jibiinkoka Gakkai Kaiho, December 1996 99:12, 1772-9) compared with 76% of Bell's palsy.
In conjunction with the early theory of J. Ramsay, the presence of herpes zoster varicella virus has been confirmed more recently in patients having Ramsay Hunt according to studies by Robillard (Robillard R B et al. Otolaryngol Head Neck Surgery:292-297, October 1986) and Wackym (Wackym, P A, Molecular Temporal Bone Pathology: II Ramsay hunt Syndrome, Laryngoscope, 1997; 107:9 1165-75, September 1997). In Wackmyn's study the DNA was confirmed in the temporal bone sections in the geniculate ganglia thereby strongly supporting the hypothesis put forth by Ramsay, and which revealingly is within the areas of the temporal bone that Hilger and Blunt maintained are affected in Bell's palsy namely the petrosal and stylomastoid arteries. In recent years the use of acyclovir has been used often in combination with prednisone (Murakami, S et al., Treatment of Ramsay Hunt Syndrome with Acyclovir Prednisone, Significance of Early diagnosis and Treatment, Ann. Neuro; 41(3): 353-357, March 1997) in order to treat Ramsay Hunt, paralleling this current treatment of Bell's palsy. Steroid therapy has also been applied (Adour K K and Hetzler D G, Current Treatment for Facial Palsy, Am J Otol, 5(6):499-502, October 1984) as well as the use of other therapies discussed for Bell's Palsy i.e. surgical decompression and electrical stimulation. As with Bell's palsy, there is no conclusive studies on these techniques and anecdotal evidence is at best mixed for this more severe condition. Eye patch treatments due to loss of blinking reflex have been incorporated as in Bell's palsy. Further with regard to the vertigo of Ramsay Hunt, diazepam has been utilized to control this symptom. In summation there is a clear overlap of Ramsay Hunt with Bell's Palsy with regard to past theory and proposed treatment.